Yes. For 240, you don't need a neutral. Aside from that, some
installations include the white wire, but it is left unconnected
at both the panel and the baseboard.
But - there's always a but - you can't just willy-nilly add a
240 volt receptacle. You have to remove the heater. There are
(or were in the past) some baseboard heaters that include a 240V
receptacle and a double pole double throw center off switch.
Without the switch, a receptacle can ba a physical part of
the baseboard gheater, but must be powered from a separate
circuit. See NEC article 210.52
The white wire is required to be re-identified when it is
used as a non-grounded conductor. Usually that is done by
wrapping it (in the j-box) with black or red tape. If you
find the white wire is one of the 240 volt legs, it's a code
violation. See NEC articles 200.6 and 200.7. If you find
it frequently, someone is worse than careless. He/she either
doesn't know what is required, or doesn't give a damn.
Probably should have mentioned what I wanted to do. Want to add a 400 or
1000watt Metal Halide light to a solarium. Unfortunately the 120v outlet
would be pushed to capacity. I wanted to run the ballast off the 240v
supplied to the baseboard heater which is never used. I would remove the
heater and add the proper box and receptacle.
The schematic on the ballast has a tap for 240 v but the return is labelled
"Common" which I assume is a neutral. Is this still ok.
ps. The wiring to the baseboard is 3 wire, two black and a ground.
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.